As the feature size of integrated circuits continues to decrease, it becomes more difficult to fabricate certain structures than others. For example, when feature sizes are reduced in size by 70 percent, the two-dimensional dimensions (such as the surface area) of contacts and other structures are actually reduced by 50 percent. Extremely small (ultrasmall) contacts and other structures can be very difficult to create due to difficulties that may arise in creating an appropriate photomask that can be used to print the ultrasmall contacts. When creating ultrasmall contacts, for example, extremely small pinholes need to be created in the photomask, which can lead to imaging difficulties. Furthermore, if the ultrasmall contacts need to be placed close together, their close proximity may cause imaging problems.
A technique that can be used to create the ultrasmall devices involves the use of charged particle and other exotic lithography techniques. These techniques can permit the creation of the desired devices.
One disadvantage of the prior art is that the use of exotic lithography techniques can significantly increase the fabrication costs when compared to standard (and well known) lithography techniques. Since the exotic lithography techniques are not as well tested or developed to help reduce costs, this can increase the overall cost of the integrated circuitry.
Yet another disadvantage of the prior art is that multiple exposures may be needed to print the ultrasmall devices, which can increase the fabrication time and result in reduced production numbers as well as increased costs.